Study On Construction Control Of Prestressed Concrete Continuous Rigid Frame Bridge With High Pier And Large Span

High-pier, large-span, continuous rigid-structured bridges are an important bridge type and are typically built using cantilever construction method. Sanshuihe Bridge, an extra-large continuous rigid-structured bridge on Xianyang-Xunyi Expressway, is such a bridge that combines high piers, long multi-span, and large spans. This paper draws on the construction of this bridge and also on the real-time monitoring of the on-site construction activities. Having regard to relevant questions collected, research has been made on and comparison has been made with monitoring data of continuous rigid-structured prestressed concrete bridges in China and in the rest of the world. A numerical simulation model was constructed using MIDAS/civil, a finite element software package, and was applied to monitor the entire process of bridge construction from the fabrication of box girder segments to the closure of the bridge. The results suggest: Sanshuihe Bridge, completed using cantilever construction method, satisfies the construction control requirements prescribed in General Code for Design of Highway Bridge and Culverts(JTG D600-2004) and Code for Design of Highway Reinforced concrete and Prestressed Concrete Bridge and Culverts(JTG D62-2012).The study covered specifically:Description of the basic principle of bridge construction monitoring and control,brief review of the development history and current state of construction monitoring technology for continuous rigid-structured high-pier, large-span, and prestressed concrete bridges in China and in the rest of the world.MIDAS/Civil was used in constructing a numerical simulation model, which was used to simulate construction control of the bridge elements. Stresses and deflections were evaluated and compared with the measured construction monitoring data, and themodel parameters were then adjusted accordingly to keep the model in agreement with the actual situation, thereby helping place a theoretical and computational basis for construction control of this type of bridge structure.Based elevation change data box girder construction process, MIDAS finite element model using data parameter identification, analysis, and then provides the basis for the next correction box girder formwork beam segment elevation, to guide the construction, construction, results showed: bottom line well into rear beam bridge,meets the design requirement.In order to make the box girder stress within a secure area, we make an analysis of the collected statistics of box section(12 multiply 2). The results show each construction stage is normal. the stress state of the box girder in every construction period meets the requirement.Under the condition of temperature gradient load, the top plate and bottom plate are subjected to compression stress and tensile stress, and the maximum stress is located in the middle of the bridge. By software simulation, The maximum compression stress of top plate and bottom plate are 11.4MPa and 12.9MPa under the load combination(including temperature gradient load), The measured values of the top plate and bottom plate of 12# pier 10# box girder are 12.84 MPa and 8.52 MPa at 3 P.M, which meets the requirements of the specification. The temperature stress on the bridge produced the downward deflection and the deflection value is 21.7mm.Xianyang area for this type of reasonable temperature gradient box girder bridges studied: we monitor the temperature of the concrete box girder within 24 hours. On the basis of the classic thermodynamics theory, ANSYS model established, we get the temperature field of this bridge in the most unfavorable moment(15:00) in summer by using the transient thermal analysis. Compared with the temperature between theory and reality, correction, optimization model, we gradually get the distribution chart of the summer concrete box girder temperature field that is suit for this area. Finally, we compared the highway standards at home and abroad, proving that this temperature gradient numerical simulation model is more reasonable.We also make a theoretical analysis of the closure of bridge process: when joining the two sections of a bridge, we make a monitor of the altitude of the slab beam,stress-strain and temperature field; after finishing the closure, were analyzed by finite element software verification results show that the theoretical calculation accuracy expectations.